Air Conditioner Buying Guide

One of the most important appliances a homeowner can purchase, an air conditioning system not only helps to lower and regulate internal air temperatures, it can help raise the overall air quality in your home. Many modern air conditioners can also be used for heating, air filtration, ventilation, air movement, humidification, and dehumidification, as well as cooling. A proper air conditioning system can be just as important as a reliable heating system, and they both can come packaged as one unit. A complete heating, ventilation, and air conditioning system can seem similar to a regular air conditioning appliance, but they are considered different and separated into the categories: HVAC and AC.

For general use, AC systems are used for lowering the inside temperature of a room or an entire house. Most AC devices usually cool the zone by using a refrigeration cycle, evaporation process, or free cooling method. The majority of air conditioners only use a few simple components, including an air compressor, a cold interior coil or evaporator, a hot exterior coil or condenser, fans, and an expansion valve.

In a refrigeration cycle air conditioner the compressor converts refrigerant gas into a liquid state, and the liquid is pumped into the cooling coil where it expands into a gas. The expanding gas then absorbs heat from air that’s being blown over the coil. The expansion valve regulates the amount of liquid refrigerant that passes through the system, and is placed between the condenser and the evaporator. The system is closed, and the refrigerant continuously circulates through a series of tubes to all the components. As a side effect, moisture from the air is condensed as the air passes over the refrigerant, and the condensed water vapor is routed to a drip pan or drain. On most AC systems, the water evaporates over time, but some models require the user to empty a water tank like they would have to with a dehumidifier. More on how air conditioners work here.

The Different Types of Air Conditioners

While there are several types of residential air conditioning unites, one design is not innately better than the other. Every model has its own strengths, weaknesses, and recommended purpose. When purchasing an AC system, make sure that it is appropriately sized for the room you want to cool. An AC unit that is too large will be inefficient, and cost the user extra money without providing a better experience (see wiki).

Portable Air Conditioners

Units that can be moved from room to room on wheels or casters are referred to as portable air conditioners. Sometimes called personal air conditioners, these units are typically used to cool single rooms that measure 450 to 550 square feet. The device itself sits on the floor and blows cool air into the center of the room. Similar to other compressor-based air conditioning systems, hot air is drawn in through the system and vented through an exhaust. One of the main differences between a portable air conditioner and a conventional window-based system is the way the portable system vents warm air. The portable device uses a vent hose that connects to the back of the unit to blow warm air out of a window. The cool air blows out of the front of the unit, similar to other AC systems.

Most portable air conditioners lower the overall humidity by condensing water vapor that’s drawn into the system. Some units have a no-drip feature, which means that the user doesn’t have to worry about loose water in the machine, but other systems come with a drip pan in the bottom of the unit. No-drip ventilation systems pipe the moisture through the hot air exhaust system. In very humid environments, no-drip devices that cannot expel all the moisture usually come with a backup drip pan. Most drip pans don’t need to be emptied, because the water evaporates after a short amount of time, but some systems come with a small water tank that needs to be emptied periodically.

Portable air conditioning systems are usually heavy, with some models weighing as much as 100 pounds. The heaviest units usually become a permanent fixture and can be used to cool an entire floor effectively. Smaller portable air conditioners cannot cool large rooms, but they can be used in tandem with other systems. To avoid getting in too much warm air from outside, you can buy window covers to seal off the open window. These are specially made so that the exhaust blows the air outside but prevents warm outside air coming into the room. Think about buying an Energy Star air conditioner (info) so you know your electricity bill won’t go sky-high.

Window-Mounted Air Conditioners

When the user needs to cool a single room, a window-mounted air conditioner is usually a good choice. Ever component is combined in a small cabinet, which can be installed in a standard window frame. Many units can be adjusted to suit the size of the window, so you don’t have to worry if the device is too small for the window. The device’s hot air vent is blows air through the back of the device into the outside air, and the condenser and fans are located in the front of the unit. The device can recalculate indoor air and expel heated air without any additional ductwork. This means that the unit can be used right out of the box.

Sometimes called through-the-wall units, window air conditioners are good at cooling relatively small rooms. They’re usually much more competitively priced than other types of air conditioner, and they’re easier to operate. Many window AC units can be plugged directly into a standard electrical outlet, but some larger models require a dedicated 115-volt or 230-volt circuit. Many of the units come with a dedicated air filter that should be cleaned in accordance with the manufacturer’s instructions. Window units can be less energy efficient than larger ducted systems, but if you simply want to cool one room, many prefer a window air conditioner.

Mini Split Air Conditioners

A step down from a full-on central air system, mini split air conditioners use interior cabinets installed on a wall or ceiling to emit cold air while the compressor runs outdoors. A conduit that contains electrical wiring and miscellaneous tubing is drilled through the wall to connect the two units. Mini split air conditioning systems are available for a single room or multiple rooms, depending on what type of package you purchase. For multiple room units, each wall-mounted cabinet is connected to a single outdoor compressor, and the temperature is regulated independently for each room. Up to four different units can connect to a single compressor.

One of the main advantages of a mini split system is that installation doesn’t require any expensive ductwork. In a larger HVAC system, ducts would have to be routed through attics, walls, and under floors, which can cost a great deal of money. Mini split systems are also very quiet, because the noisy compressor is located outside the building. Mini split systems are often used to cool entire floors, but they are sometimes used to augment the efficiency of existing cooling systems.

Central Air Conditioners

Also known as a heating, ventilation, and air conditioning system, or HVAC, central air conditioners distribute air to multiple rooms by using a series of ducts. A central air conditioning system can be costly to install, but are the most efficient at keeping a house cool. Central air conditioners are quiet because the compressor is located away from living spaces while the air travels through the same ducts that are used for heating and ventilation.

Central air conditioners are designed as either a split system, or a package system. A split system has an indoor cabinet that houses the cooling element and an outdoor unit that houses the compressor and condenser. In a split system, the indoor cabinet would also include a furnace that would be used during the cooler months to heat the house. The outdoor condenser unit usually uses the same ductwork as the heating system so secondary vents don’t have to be run for each device. Package systems combine the air conditioning components and the compressor into one unit, which is usually located outside the house or on the roof.

Information About Heat Pumps

It may seem counter-intuitive, but heat pumps can also be used for air-conditioning as well as heating. Heat pumps use electricity to transfer heat from a cool space to a warm space. During the winter, heat is transferred indoors, and during the summer, the heat is routed outside. There are several types of heat pumps, but they all operate on a similar principle. Much like a compressor-based air conditioning unit, a heat pump passes liquid refrigerant through a compressor, which then expands to a gas and absorbs heat (info).

Ground-source heat pumps extract heat from the ground or from an underwater water source and transfer the heat indoors. These systems are efficient dehumidifiers, but some users complain they don’t work as well as an air conditioner. Mini split heat pumps operate like a regular mini split air conditioner, except it uses the heat pump process to transfer heat from one place to another. Mini split heat pumps are also ductless, so they can help reduce the setup and maintenance costs.

Heat pumps work best in moderate climates, so if you live in an area with very cold winters or very hot summers, the device won’t be as effective as other heating and cooling sources. One major plus of using a heat pump is that the user can save up to 40 percent on electricity if the device is properly maintained.

In this youtube movie you can watch more on how air conditioners work.

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